I think you're reading way too much ("slow, deliberate, condescending") into what is just normal behavior. Everybody blinks.
It was the blink together with the facial expression. That plus knowing who she is and how people of her type generally think about people on the right, especially on issues like this one, where they are 110% convinced it is truth and deniers are stupid and/or nuts.
It was a look like, “Yeah, go ahead, let’s hear what you have to say”, while thinking to herself, “I know it’s going to be some kind of anti-warming BS”.
Watch it on full screen. At just about the 2-sec mark in the video she does the blink and at the same time makes a face, IMO, revealing, be it subtly, her inner expectations of what Carly is going to say.